Methods and Means for Improvings Resin Bonds Between Substrates, and Materials Therefor and Products Therefrom

1. Field of the Invention

This invention pertains to the adhering of substrates to one another, and is particularly but not exclusively applicable to the adhering of fibrous material to elastomers, more particularly with the aid of adhesive dips dried on the fibrous material before assembly to the elastomer and vulcanization thereof; and to the provision of adhesive compositions therefor.

2. State of the Prior Art

It is known to pretreat various substrates, e.g. fibrous material, with adhesive resorcinol formaldehyde resin (RF) dips, with such RF dips containing a proportion of elastomer latex (RFL dips), and/or with epoxy resin dips, and to dry the same on the fibrous material before assembling the same with another substrate, e.g. a vulcanizable elastomer and curing the same, for the purpose of providing a bond between the substrates, and especially between a vulcanizate and the fibrous material. Examples of such treatments are disclosed in British Pat. No. 1,141,807 published Feb. 5, 1969.

The present invention aims to promote or increase the strength of the bond obtained between substrates with the aid of phenoplasts, modified phenoplasts and/or epoxy resins, e.g. between fibrous material and an elastomer on vulcanization thereof, and this object is accomplished in accordance with the present invention, by applying to the substrate, in addition to a preformed phenoplast, modified preformed phenoplast, and/or preformed epoxy resin, and drying thereon before the assembly thereof with the other substrate, as an adhesion promoter, a quantity of z-aminophenol, which may be blended in a phenoplast adhesive, such as an RF dip or an RFL dip, or may be blended in the elastomer latex used for forming an RFL dip, and such blends constitute useful combinations embraced in the invention.

In the following detailed description generic and subgeneric terms are employed according to the following definitions:

1. Rubber or elastomer

The terms "rubber", "rubber material", "elastomer", and "elastomer material" are used herein to designate elastomeric materials or rubbery materials including natural rubbers and the synthetic rubbers which are capable of being cured or vulcanized, as by the aid of heat and suitable vulcanizing agents. The vulcanizing agents, depending on the particular elastomer, may be of the sulfur type and/or of the free radical type, e.g., the peroxide or hydroperoxide type, and/or of other types. Such rubbers include homopolymers and copolymers of conjugated dienes such as polychloroprene, polybutadiene, polyisoprene and copolymers of chloroprene, butadiene and isoprene with vinyl monomers, such as the copolymers of butadiene-styrene, butadiene-acrylonitrile and the like, copolymers of isobutylene and isoprene (the butyl rubbers), copolymers of ethylene and propylene, terpolymers of ethylene, propylene and a non-conjugated diene and other elastomers, e.g. fluorocarbon elastomers, as Viton B or Fluorel.

The term "vulcanizable elastomer" as used herein designates a rubber compound with suitable compounding ingredients including a vulcanizing agent so as to be capable of being cured or vulcanized, as by the aid of heat. The vulcanizable elastomer may be applied in any suitable manner, e.g. by calendering, pressing in a mold or deposition from an aqueous or solvent dispersion.

2. Fibrous Materials

The generic term "fibrous material" as used herein is applicable to natural and synthetic fibrous materials, e.g. reinforcing material in the form of filament, yarn, cord, cable, ribbon, and cord fabric unwoven or woven as cloth or canvas to be used in reinforcing rubber articles such as vehicle tires, mechanical rubber goods such as belts, hose, gaskets, and the like, or as carrier sheet for adhesive material for interposition between other substrates to be bonded together thereby. Such fibrous materials may consist of cotton, cellulose acetate, organic esters and ethers of cellulose, rayon, polyesters such as ethylene glycol terephthalic acid polyesters (Dacron), the polyvinyls and/or polyvinylidenes, such as the acrylonitrile polymers (Orlon), polyvinyl chloride and vinylidene chloride polymers (Vinyon), the polyethylenes and other polyolefins, the polyurethanes (Perluran), the proteins (Caslen), alginates, mineral fibers (fiberglass), polyamides, such as the aliphatic dicarboxylic acid-polyamide reaction products (nylon) and polyvinyl alcohol and combinations of two or more different fibers e.g. in the same yarn or fabric.

The sub-generic term "polyester fiber" as used herein and in the art (see H. Ludewig "Polyester Fasern Chemie and Technologie," published by Akademie Verlag, Berlin, Germany, 1965 herein incorporated by reference) connotes fibers of linear polymeric polyesters containing the ester linkage in the main chain. Such fibers include those produced by reacting glycols such as ethylene glycol, propylene glycol, methoxypropylene glycol with carboxylic acids and typical of these is Dacron, which is a polyethylene glycol ester of terephthalic acid.

The sub-generic term "polyamide fiber" as used herein and in the art (see H. Klare, E. Pritzache and V. Grobe "Synthetische Fasern aus Polyamiden Technologie and Chemie", published by Akademie Verlag, Berlin, Germany, 1963, herein incorporated by reference) designates the synthetic fiber-forming polyamides. Such polyamides are for example those produced by the condensation of a dicarboxylic acid and a diamine, typically exemplified by polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecanediamide (nylon 612) and polycaproamide (nylon 6).

The sub-generic term "glass fiber" as used herein applies to continuous glass fibers and discontinuous glass fibers in the form of filaments, strands, yarns, bundles, cords and fabrics formed therefrom and includes crimped and uncrimped fibers, strands, yarns and threads and those which have been plied or twisted in multiple groups to form yarns, cords or fabrics, this term includes such glass fibers coated with sizing compounds or bonding agents or coupling agents or anchoring agents. Illustrative of such coating agents are organic trivalent chromium compounds e.g. methacrylato chromic chlorides or stearato chromic chloride; titanium complexes e.g. titanium tetraesters; silane and siloxane compounds e.g. the vinyl and allyl trialkoxy silanes, the aminoalkyl and acryloxyalkyl trialkoxy silanes, and other organic silicone compounds described in U.S. Pat. Nos. 3,484,223, 2,563,288, 2,688,006, 2,688,007, 2,723,211, 2,742,376, 2,754,237, 2,776,910, 2,799,598, 2,832,754, 2,930,809, 2,946,701, 2,952,576, 2,974,062, 3,044,982, 3,045,036, 3,169,884, 3,207,623, 3,211,684, and 3,459,585, herein incorporated by reference.

3. Epoxy Resins and Epoxy Resin Coatings.

The term "epoxy resin" as used herein connotes a component for coating substrates, e.g. fibrous materials, consisting essentially of organic material having at least 2 epoxy groups, i.e. ##STR1## groups per molecule, or of such material in combination with diisocyanate material, e.g. "Hylene MP" commercially available from the duPont Company. Such epoxy resins may be obtained by reacting for example epichlorohydrin with a polyhydric phenol such as bis-(4-hydroxyphenyl)-2,2-propane, bis (hydroxyphenyl) methane. Examples of such compounds are described in U.S. Pat. Nos. 2,324,483; 2,444,333; 2,494,295; 2,500,600; 2,511,913; 2,943,095; 2,872,427; 3,488,314; 1,888,358; 2,943,095, and 3,525,703 herein incorporated by reference; and the commercially available epoxy-resins are included hereunder as for example the ERL resins sold by Union Carbide Corporation under the trade names "ERL 2774", "ERL 3794", "ERL 2794", "ERL 4289", and "ERL 2774", the Epen resins, sold by the Shell Chemical Company, i.e., Epon 1001, Epon 1004, Epon 1007, Epon 1009, Epon 815 and Epon 828; the Araldite resins sold by the Ciba Company, Inc. designated as Araldite 6010, Araldite 502 and Araldite 6020, and GenEpoxy Resins sold by General Mills Chemical Division, i.e. GenEpoxy 175, 190, 525 and M-180, and others. The epoxy resin compounds which are insoluble in water may be supplied as a dip in the form of a solvent solution or an aqueous emulsion or a colloidal dispersion.

4. Dips.

The term "dip" as used herein includes aqueous or non-aqueous solutions, suspensions or emulsions which may be applied to substrate material by dipping, spraying, padding or other suitable procedures, followed by drying.

5. Dried or Drying.

The term "dried" or "drying" as used herein includes drying at ambient temperatures and/or elevated temperatures under atmospheric, subatmospheric or elevated pressures, in air or other, e.g. inert, atmosphere; and at the elevated temperatures is preferably accompanied by partial curing of the components by heat and/or with the aid of curative ingredients.

6. Epoxy resin coating.

The term "epoxy resin coating" as used herein means a coating, preferably at least partially cured, of epoxy resin on the substrate material. For forming an epoxy resin coating, an epoxy resin may be applied to a substrate material as a dip in any suitable manner, e.g. per se or as a solution in a volatile solvent such as acetone, methyl ethyl ketone, or chloroform or as a water emulsion or dispersion, and preferably is then at least partially cured, preferably with the aid of a curative of the acid or basic catalyst type, with the latter being preferred. Typical of such catalysts are those set forth in U.S. Pat. No. 2,872,427, herein incorporated by reference, such as ethylene diamine, diethylene triamine, triethylene tetramine, dicyandiamide, melazine, pyridine, cyclonexylamine, benzyldimethylamine, benzylamine, diethylaniline, triethanolamine, piperidine, tetramethyl piperazine, N,N-dibutyl-1,3-propane diamine, N,N-diethyl-1,3-propane diamine, 1,2-diamino-2-methylpropane, 2,7-diamino-2,6-dimethyloctane, dibutylamine, dioctylamine, dinonylamine, distearylamine, diallylamine, c-tolylnaphthylamine, pyrrolidine, 2-methylpyrrolidine, tetranydropyridine, 2-methylpiperidine, diaminopyridine, tetraethylpentamine, meta-phenylene diamine, and salts of such amines, and other epoxy resins and catalysts as described in H. Lee and K. Neville's treatise entitled "Handbook of Epoxy Resins", herein incorporated by reference.

7. Phenoplasts.

The term "phenoplast" or "phenoplasts" as used herein include those resins which are basic catalyzed reaction products of a phenol and an aldehyde (i.e. the resoles and resitols) and those resins which are acid catalyzed reaction products of a phenol and an aldehyde (e.g. the novolacs). Thus the term "phenoplasts" is used in the accepted sense as set forth in the treatise entitled "Phenoplasts" by T. S. Carswell published in 1947 by Interscience Publishers, Inc., New York, N.Y., which treatise is herein incorporated by reference.

Suitable phenols to form the phenoplasts hereof include phenol; dihydric phenols such as resorcinol; substituted phenols such as the alkylated phenols exemplary of which are m-cresol, o-cresol, m-ethylphenol, m-n-propylphenol, m-isopropylphenol, m-n-hexylphenol, m-n-butyl phenol, m-sec-butyl phenol, m-tert.-butyl phenol, m-amyl phenol and other like phenols, particularly those wherein the alkyl substituent contains from 1 to 9 carbon atoms inclusive; the meta-substituted phenols such as m-aminophenol, resorcinol monoacetate, 1,5-naphthalenediol and the like; meta-substituted alkoxy phenols such as m-methoxy phenol, m-ethoxy phenol, m-n-propoxy phenol and the like, particularly those wherein the alkoxy group contains from 1 to 6 carbon atoms inclusive; as well as those phenols with similar substituents in the para-position (e.g. p-tert.-butyl phenol) which are suitable for forming novolacs; the polyhydric polynuclear phenols which consist of two or more phenols connected by such groups as methylene, alkylene or sulfone, such as bis(p-hydroxyphenyl)-methane, 2,2-bis(p-hydroxyphenyl) propane and dihydroxydiphenyl sulfone and the like; and the halogenated phenols and polynuclear phenols including the meta-halogenated phenols such as m-chlorophenol, m-bromophenol and the like.

The monohydric, mononuclear phenols suitable to form the phenoplasts herein can be represented by the following formula: ##STR2## wherein R is an alkyl radical containing from 1 to 9 carbon atoms inclusive or an alkoxy radical containing from 1 to 6 carbon atoms inclusive; R' is a halogen atom, i.e. chlorine, bromine, iodine or fluorine; and n is an integer having a value of 0 to 1 inclusive.

Suitable aldehydes to form the phenoplasts hereof include formaldehyde in any of its available forms, (i.e., formalin, paraformaldehyde and trioxane), furfural, glyoxal, acrolein and the like.

8. Novolac Resins.

The terms "novolac" or "novolac resin" are used herein in the accepted sense employed in T. S. Carswell's treatise "Phenoplasts" referred to above. Thus, the novolac resins are well known phenoplast products which are usually acid-catalyzed phenol aldehyde condensates, and which are prepared by condensing a phenol and an aldehyde in the presence of an acid such as oxalic acid, sulfuric acid, hydrochloric acid and the like or in the presence of a metal salt of an acid such as zinc acetate, wherein the phenol is present in the reaction mixture in more than stoichiometric amounts. Novolac resins can be converted to the infusible state by the addition thereto of a cross-linking agent such as a methylene generating agent such as hexamethylenetetramine.

The following commercial resins used in certain of the examples hereinafter are reported to be novolac resins:

(a) The trademark product Durez 12686, a cashew nut oil modified phenolic novolac resin (used in Table XX, examples 75-78),

(b) the trademark product Durez 22193, a thermoplastic resin cured with the aid of a polyamide resin (used in Examples 83-85, Table XXII);

(c) the trademark product Penacolite R-2170, a 75% aqueous solution of a resorcinol-formaldehyde condensation product requiring the addition of a methylene donor to become thermo-setting (used in Examples 79-82, Table XXI).

9. Methylene donor.

The term "methylene donor" as used herein includes those compounds which provide methylene linkages in reacting with soluble or plastic or heat softenable phenoplasts, e.g. A-stage resins (resoles) or B-stage resins (resitols), or novolacs to form cross-linked insoluble, infusable resins, e.g. C-stage resins (resites). Such methylene donor material include hexamethylenetetramine (hexa), as well as formaldehyde, which term includes formaldehyde and various polymeric forms thereof such as paraformaldehyde, trioxane and the like.

10. RF Resin.

The term "resorcinol formaldehyde resin" or "RF resin" as used by the trade and herein means an acid or basic catalyzed phenolic resin which consists essentially of the reaction product of a substituted phenol and an aldehyde, heat hardening per se or with the aid of a methylene donor and/or metal oxide. Suitable substituted phenols include phenols having substituents selected from the groups consisting of --OH, --NH.sub.2 or --OCOCH.sub.3 groups, such as resorcinol, n-aminophenol, resorcinol monoacetate, 1,5-naphthalenediol and other typical phenols employed to form phenolic type adhesives and combinations of such phenols. Suitable aldehydes for the reaction include furfural, acrolein, glyoxal, and especially formaldehyde which may be employed as formalin (37% by weight formaldehyde gas in water), and combinations of two or more thereof. The resin forming reaction is preferably carried out in water with the aid of an alkali metal hydroxide or carbonate such as sodium hydroxide or sodium carbonate; or with aqueous ammonia; or with a water sluble or dispersible amine such as monoethanolamine, diethanolamine, triethanolamine, and/or the unsaturated amines such as diallylamine, triallylamine, and the vinylamine monomers, e.g. t-butylaminoethyl methacrylate and dimethylaminoethyl methacrylate. The RF resin may be applied to the fibrous material or pretreat fibrous material in the form of a dip and dried thereon as above described.

11. Phenoplasts modified with Modifying Polymer.

In connection with adhesive compositions herein, the terms "phenoplasts modified with modifying polymers" or "modified phenoplasts" are used to refer to "phenoplasts" plus "modifying polymers", e.g. synthetic rubbers and thermoplastic resins which may be employed to improve flexibility and adhesion to particular substrates, including but not limited to natural rubber; polybutadiene; polyisoprene; polychloroprene; butadiene/acrylonitrile, butadiene/vinyl pyridine, butadiene/styrene/vinyl pyridine, butadiene/styrene, isobutylene/isoprene, and other hydrocarbon diene/vinylidene interpolymers; ethylene/propylene and other alpha olefin polymers and interpolymers; the foregoing polymers and interpolymers provided with carboxyl groups; and combinations of two or more of the foregoing. Thus the modified phenoplasts include compositions comprising phenoplasts and modifying resins selected from the class consisting of the members of the following groups:

(1) polychloroprene (Neoprene elastomer);

(2) butadiene-acrylonitrile copolymers (nitrile elastomers);

(3) butadiene-styrene copolymers;

(4) thermosetting or curing epoxy resins;

(5) thermoplastic vinylidene resins, including vinyl resins, e.g. polyvinylformal resins,

(6) thermoplastic polyamide resins;

(7) other known polymeric materials suitable as modifiers for phenoplasts;

(8) combinations of two or more of the foregoing polymeric modifiers.

See "Adhesive Guide" by Joyce Hurd, B.S.I.R.A. Research Report M-39, 1959, The Cable Printing & Publishing Co., Ltd., London, herein incorporated by reference.

12. Adhesive Composition.

The term "adhesive composition" as used herein includes phenoplasts with and without modifying polymer dispersed in a liquid dispersing medium, or carried by a carrier sheet. In the liquid dispersion form it is exemplified by the resorcinol formaldehyde (RF) dips, and the resorcinol formaldehyde elastomer latex (RFL) dips. The adhesive composition is applied as a liquid dispersion in a liquid dispersing medium and said liquid is preferably a volatile organic liquid such as an aliphatic or aromatic hydrocarbon, an alcohol such as ethanol, propanol, isopropanol or the like, or a ketone such as acetone, methylethyl ketone, diethyl ketone or the like and most preferably the liquid dispersing medium is aqueous. When the adhesive composition is aqueously dispersed then a cationic or anionic and/or non-ionic dispersing agent may be employed. The liquid dispersed adhesive phenoplast (modified or unmodified) compositions, in uncured or partially cured form may be applied to a substrate, which may be selected from the class consisting of plastic film, woven fabrics, non-woven fiber sheeting, and metal foil, and may be dried thereon for application as a sheet to be interposed between substrates to be joined by curing thereof. The liquid dispersed epoxy resin adhesives may be similarly applied except that they must be at least partially cured before being contacted with the m-aminophenol promoter.

13. RFL Dips.

The RF resin is preferably employed with an elastomer latex and such combination is referred to by the trade and herein as "RFL" or as an RFL dip. The elastomer latices employable in such RFL combinations include natural Hevea latex, natural rubber latices grafted with vinyl compounds such as methyl methacrylate, vinylpyridine, etc., and various synthetic rubber latices such as homopolymer latex of a C.sub.4 to C.sub.10 conjugated diene compound, and copolymer latices obtained by the copolymerization of a C.sub.4 to C.sub.10 conjugated diene with one or more vinyl monomers such as styrene, vinylpyridine, acrylonitrile, acrylic acid, methacrylic acid, alkyl acrylates and alkyl methacrylates and the like, e.g. styrene-butadiene copolymer latex, polybutadiene latex, polyisoprene latex, polychloroprene latex, isoprene-isobutylene copolymer latex, butadiene-acrylonitrile copolymer latex, butadiene-methacrylic acid copolymer latex, butadiene-styrene-acrylic acid copolymer latex, and a preferred elastomer latex is a vinylpyridine latex, usually used in combination with another elastomer latex, for example as described in U.S. Pat. No. 2,561,215, herein incorporated by reference, wherein the vinylpyridine latex comprises an aqueous dispersion of a copolymer of 50 to 95 percent by weight of a conjugated diolefin having 4 to 6 carbon atoms, 5 to 40 percent of a vinylpyridine, and 0-40 percent of a styrene, and suitable vinylpyridines are 2-vinylpyridine, 2-methyl-5-vinylpyridine and 5-ethyl-2-vinylpyridine. Such a vinylpyridine latex is commercially available as "Gen-Tac", a trademark product of General Tire and Rubber Co., which is reported to be a vinylpyridine latex consisting of a copolymer of 70% butadiene, 15% styrene and 15% 2-vinylpyridine having a total solids content of around 40 percent. It is usually desirable to blend the vinylpyridine latex with an SBR rubber latex as for example a blend of 70 to 80% of an SBR rubber latex and 20 to 30% by weight of the vinylpyridine latex. The elastomer latex component of an RFL dip may be added to a preformed RF resin as an aqueous dispersion, or the RF resin may be prepared in the presence of the elastomer latex. The RFL dip may be applied to the fibrous material or pre-treated fibrous material and be dried thereon as above described.

14. Adhesion Promoter.

The "adhesion promoter" of the present invention is m-amiophenol as hereinafter defined, applied in conjunction with an adhesive used to bond together composite structures and/or substrates and said adhesive preferably being a phenoplast resin with or without modifying polymer. In particular applications such adhesive promoter is applied to fibrous materials in a manner to improve the bond strength developed between the fibrous material and an elastomer material by a dried epoxy resin and/or RF or RFL resin composition.

15. M-aminophenol.

The term "m-aminophenol" as used in the present invention includes m-aminophenol (i.e. 3-aminophenol or m-hydroxyaniline) and its salts with acids having an appreciable water solubility, i.e. including the "water soluble acids" which include "water soluble mineral acids" and "water soluble organic acids". The water soluble mineral acids comprise sulfuric acid, hydrochloric acid, and the like. The water soluble organic acids comprise, but are not limited to, the water soluble, aliphatic monocarboxylic acids, e.g. the alkenoic acids of 1 to 3 carbon atoms (formic, acetic, and propanoic) and the water soluble, hydroxylalkanoic acids such as hydroxyacetic acid, 2-hydroxypropanoic acid, 3-hydroxypropanoic acid, the hydroxybutanoic acids, 2,3-dihydroxypropanoic acid, and citric, oxalic, malonic, maleic, fumaric, acrylic, methacrylic acids and the like. The m-aminophenol may be applied to a substrate prior to, concurrently with, or subsequently to the application thereto of the preformed phenoplast, and the material may be dried thereon sequentially or concurrently to prepare the composition.

16. Substrate.

The term "substrate" as used herein refers to any solid material, e.g. fibrous material, sheet material, structural elements of wood, metal and/or plastic, including but not limited to, the fibrous or sheet material as set out under (2) and (12) above to which the adhesive compositions of the present invention may be applied and dried in uncured condition, and which may become a part of a composite structure when the adhesive composition is cured.

17. Composite structure.

The term "composite structure" as used herein connotes any structure comprising a plurality of substrate elements or members assembled with adhesive material according to the invention.

In a first aspect of the method category of this invention, in the formation of a bond by vulcanizing a vulcanizable elastomer to a fibrous material with the aid of an adhesive dip of resorcinol formaldehyde resin with or without a quantity of elastomer latex dried on the fibrous material before assembly with the elastomer and vulcanization thereof, which fibrous material may also have been treated with a dip of epoxy resin and dried, to improve the bond there is also applied to the fibrous material, and dried thereon before such assembly, a dip of m-aminophenol. The ratios of the coating components on the fibrous material applied as individual or combined component dips are preferably as follows: epoxy resin (dry basis) 0-2 parts by weight; resorcinol formaldehyde resin (dry basis) 1 part by weight; elastomer latex (dry basis) 0-15 parts by weight; m-aminophenol (dry basis) 0.1 to 4 parts by weight. In the single or combined component dips a quantity of water or volatile solvent is employed in such proportion that the dry solids content of the dip is preferably in the range of 0.1% to 10% by weight.

In particular procedural embodiments of the invention the adhesive dip of resorcinol-formaldehyde resin and the m-aminophenol dip may be at least in part applied to the fibrous material and dried thereon concurrently; or the adhesive dip of resorcinol formaldehyde resin and the m-aminophenol dip may be at least in part applied to the fibrous material and dried thereon sequentially, or at least a part of the m-aminophenol dip may be applied to and dried on the fibrous material after the drying thereon of the adhesive dip of resorcinol formaldehyde resin.

In certain embodiments of the invention the fibrous material is selected from the class of fibrous materials suitable for use as tire cord consisting of the polyamide fibers, the polyester fibers and the glass fibers, with or without said fibrous material having been pre-treated with an epoxy resin dip and dried.

In an embodiment of its product aspect the invention provides a composite structure consisting essentially of a vulcanizable elastomer vulcanizate bonded to a fibrous material with the aid of an adhesive from a resorcinol formaldehyde resin dip with or without a portion of elastomer latex, particularly characterized in that the bonding of said adhesive is augmented by m-aminophenol applied to and dried on the fibrous material prior to its assembly with the elastomer and vulcanization thereof; and in another embodiment the invention provides a composite structure consisting essentially of a vulcanizable elastomer vulcanizate bonded to a fibrous material with the aid of epoxy resin adhesive and an adhesive from a resorcinol-formaldehyde resin dip with or without a portion of elastomer latex, particularly characterized in that the bonding of said adhesives is augmented by m-aminophenol applied to and dried on the fibrous material prior to its assembly with the elastomer and vulcanization thereof.

Also as useful subcombinations the invention provides:

(A) An improved adhesive composition for bonding substrates to one another, said adhesive composition being a liquid dispersion comprising, by weight, the combination of:

(a) 5 to 250 parts of liquid dispersing medium,

(b) 10 parts of phenoplast material selected from the members of the class consisting of group (I) the heat curable phenoplasts containing methylol groups; group (II) the mixtures of (1) novolac phenoplasts substantially free from methylol groups with (2) at least sufficient methylene donor material to enable heat curing of the same; group (III) mixtures of (1) phenoplasts which complex with metal oxides with (2) at least sufficient material selected from the oxides and hydroxides of the metals calcium, magnesium and zinc, to complex with the phenoplast; and (4) heat curable combinations of the foregoing.

(c) 0 to 150 parts of modifying polymer, and

(d) 0 to 30 parts of material selected from the oxides and hydroxides of the metals calcium, magnesium, and zinc,

the said composition being improved in that it contains in the combination

(e) 1 to 40 parts by weight of m-aminophenol.

(B) A composite structure comprising a substrate having such improved adhesive composition applied thereto; and especially one in which the so applied composition has been substantially freed of said liquid dispersing medium.

(C) An adhesive material for bonding substrates to one another, said adhesive material consisting essentially of

(a) a vehicle, and carried thereby, dry basis by weight, a mixture of

(b) 10 parts of heat curable phenoplast,

(c) 0 to 150 parts of elastomer,

(d) 0 to 50 parts of inorganic material selected from the oxides and hydroxides of the metals calcium, magnesium and zinc,

(e) 0 to 40 parts of donor material and

(f) 1 to 40 parts of m-aminophenol;

and especially such an adhesive material wherein said vehicle is selected from the class consisting of volatile liquid and non-volatile solid carriers.

(D) An aqueous adhesive composition comprising a mixture, dispersed in the aqueous phase, dry basis by weight, of

(a) 1 part phenoplast resin,

(b) from 0 to 2 parts epoxy resin,

(c) from 0 to 15 parts elastomer latex, and

(d) from 0.1 to 4.0 parts m-aminophenol;

and especially such an aqueous adhesive composition which contains as component (a) a resorcinol/formaldehyde phenoplast, and as component (c) from 0.5 to 15 parts vinyl pyridine latex, and/or which contains from 0.2 to 2.0 parts epoxy resin.

(E) An improved elastomer latex composition for use in preparing modified phenoplast adhesive compositions which consist essentially, dry basis by weight, of

(a) 15 parts elastomer latex, and

(b) from 0.1 to 4.0 parts m-aminophenol;

and especially such an improved composition in which at least 0.5 parts of the elastomer latex is a vinylpyridine latex, a polychloroprene latex, a butadiene-acrylonitrile latex, a latex of polychloroprene having carboxyl substituents, or a latex of butadiene-acrylonitrile polymer having carboxyl substituents, or a combination of two or more such latices.

(F) A composition for use in forming phenoplast adhesive compositions which consists essentially of a mixture of hexamethylemetetramine and m-aminophenol in the proportions by weight of from about 1 to 40 to about 40 to 1.

In more detail in certain embodiments of this invention one of the substrates, e.g. a fibrous material is bonded to the other substrate, e.g. a compounded elastomer with the aid of an adhesive system in which the adhesives are selected from the class of adhesives resins consisting of the epoxy resins, RF resins, RFL resins and combinations of such resins; and with m-aminophenol as adhesion promoter; and the examples hereinafter typify various embodiments of the invention. Among these embodiments are those employing the m-aminophenol as an adhesion promoter in the following sequences and combinations:

(i) fibrous material--epoxy resin.sup.(1) --m-aminophenol.sup.(2) --elastomer compound.sup.(6) ;

(ii) fibrous material--epoxy resin.sup.(1) -- m-aminophenol.sup.(2) --RF resin or RFL resin.sup.(3) --elastomer compound.sup.(6) ;

(iii) fibrous material--epoxy resin.sup.(1) --m-aminophenol.sup.(2) --RF resin or RFL resin.sup.(3) --m-aminophenol.sup.(4) --elastomer compound.sup.(6) ;

(iv) fibrous material--epoxy resin.sup.(1) --m-aminophenol.sup.(2) --RF resin or RFL resin plus m-aminophenol.sup.(5) --elastomer compound.sup.(6) ;

(v) fibrous material--epoxy resin.sup.(1) --RF resin or RFL resin.sup.(3) --m-aminophenol.sup.(4) --elastomer compound.sup.(6) ;

(vi) fibrous material--epoxy resin.sup.(1) --RF resin or RFL resin plus m-aminophenol.sup.(5) --elastomer compound.sup.(6) ;

(vii) fibrous material--m-aminophenol.sup.(2) --RF resin or RFL resin.sup.(3) --elastomer compound.sup.(6) ;

(viii) fibrous material--RF resin or RFL resin.sup.(3) --m-aminophenol.sup.(4) --elastomer compound.sup.(6) ;

(ix) fibrous material--RF resin or RFL resin plus m-aminophenol.sup.(5) --elastomer compound.sup.(6) ;

(x) fibrous material--epoxy resin plus RF resin or RFL resin--m-aminophenol.sup.(7) --elastomer compound.sup.(6).

The modes of realizing and embodying each of the foregoing aspects and procedures of the invention are set forth in detail in the examples 1-62, which are to be taken as illustrative and not restrictive of the invention, the scope of which is more particularly pointed out in the appended claims.

The following Examples and their tabulations demonstrate applicant's discovery of the effect of m-aminophenol as an adhesive promoter in improving the bond strength between fibrous material and elastomer material when bonded with an epoxy resin and/or with a rescorcinol formaldehyde resin with or without elastomer latex, in each of the above noted aspects, as indicated in connection with the respective groups or tables thereof.

This group of Examples comprises working examples bearing "B" numbers and comparative or control examples bearing "A" numbers, the "B" numbered examples employing the invention; and the last two columns showing by comparison with the "A" Examples the improvements effected thereby. In these Examples polyester fabrics are prepared for adhering to polychloroprene by coating a fabric such as Dacron with an emulsion of epoxy resin and a selected curative, then letting the coating on the fibrous dry and curing it for 30 minutes at 163.degree. C. In the "B" Examples such epoxy resin coated Dacron is then after-treated with an aqueous solution of m-aminophenol, allowed to dry, and laminated to a compounded Neoprene rubber sheet and cured for 45 minutes at 165.degree. C., and a high tensile strength bond occurs between the Dacron and the Neoprene. If the m-aminophenol step is omitted, as in the control or "A" Examples, the peel strength of the laminate is considerably lowered.

Examples 1 through 8 set forth in Table I also illustrate that the advantages of the invention are not dependent on the type of curative used for curing the epoxy resin, or on the level of curative employed. For this purpose four different amine curatives each at a high and low level were added to the aqueous emulsion of the epoxy resin of diglycidyl ether of bisphenol A.

When reference is made in the Tables to the "unaged peel strength" this means the peel strength determined on a sample which has not been subjected to the aging effect of prolonged immersion in hot water, e.g. 14 days, prior to the peel strength test.

In Table I-A recipe I is set forth for the preparation of epoxy resin emulsions as follows: the epoxy resin and a small amount of non-ionic emulsifier polyoxyethylene sorbitan monosteareate.sup.(1) were first dissolved in chloroform, the weight proportion being 20 parts epoxy resin, 2 parts non-ionic emulsifier, and 78 parts chloroform. These were mixed together for about two minutes in a blender, and then agitation was continued at high speed while an aqueous solution of anionic emulsifier.sup.(2) was added very slowly. This solution consisted of 2 parts lauryl alcohol sulfate.sup.(2) and 98 parts water, and then 200 parts water. Agitation was continued for another 5 minutes and then the emulsion was removed from the blender and diluted with water as desired, usually to provide a 5% epoxy resin solids emulsion.

Sixteen batches of epoxy emulsion dip were prepared according to recipe I Table I-A employing as epoxy resin a diglycidyl ether of bisphenol A having an epoxy equivalent of about 200 and viscosity about 20,000 cps. In Table I is set forth the amount of curative added to each of these batches e.g. in Example 1A and 1B to the emulsion containing 20 grams of epoxy resin was added 0.68 grams of tetraethylenepentamine.

The amine curing agents were added to the epoxy emulsions from 5% solutions of the particular amines in water or a mixture of equal parts by weight of water and isopropanol. All the epoxy emulsion examples with curatives were further diluted with water so as to contain 1% epoxy resin content by weight.

Two proportions each of four different amine compounds were used. These compounds included tetraethylenepentamine, which has both a primary and secondary amine groups; diethanolamine, a secondary amine; and piperidine and dimethylaminomethylphenol (DMP-10, Rohm & Haas Co.) which are tertiary amines. The proportions of these amines as parts by weight per hundred epoxy resin is shown in Table I and was equal to 25% and 100% of proportions commonly used in curing epoxy resins except in the case of tetraethylenepentamine which was used in amounts equal to 25% and 140% of the proportions commonly used in curing epoxy resins.

Pieces of polyethylene terephthalate, (Darcon, E. I. Du Pont de Nemours and Co. Inc.) were soaked for about a minute in various dips as set forth under fabric treatment A, Table I,.sup.(1) and then were dried overnight at ambient temperature, followed by heating for 30 minutes at 165.degree. C. to at least partially cure the epoxy resin.

Samples of each of these treated fabrics were reserved for control or comparative testing while other portions were further treated by dipping into 0.5% aqueous solutions of m-aminophenol as set forth under fabric treatment B, Table I and then dried for 16 hours at ambient temperature, after which they were again cured for 30 minutes at 165.degree. C.

The treated pieces of Dacron and the controls thus prepared were then each press-laminated with a small sheet of uncured polychloroprene compounded according to recipe A, Table IV to provide laminates.

Laminates of treated fabrics and elastomer compounds were formed by sandwiching a small rectangular piece of compound (which had been sheeted out on a rubber mill to less than an eighth of an inch in thickness) between two rectangular pieces of treated fabric about 3 by 4 inches in size and the laminates pressed together in a laboratory Carver Press for one minute at about 100.degree. C. and 460 psi. The applied pressure forces the elastomer compound into the weave of the fabric, insuring good contact between fabric and elastomer.

The laminates were then pre-heated 20 minutes at 115.degree. C. followed by curing them (usually for 60 minutes at 165.degree. C. in an air oven) without weights upon them. After curing and cooling of the laminates, specimens one inch wide were cut therefrom for peel test purposes.

The test for peel strength requires the plies at one end of the specimen to be separated for insertion into the jaws of the testing machine. To facilitate this separation, a masking strip of cellophane tape was placed across one end of one of the pieces of fabric before assembly and lamination with the elastomer compound so that the elastomer at that end adhered to only one sheet of fabric.

Peel strength was determined according to Method 5950 of Federal Specification CCT-191B, except that the speed of separation of the jaws of the testing machine (Scott Tester Model L50RR) was 2 inches per minute. One ply of the specimen was inserted in each clamp and then as the peeling of the specimen progressed, the peel strength in pounds was read directly from the dial of the machine. After values which were thought to be unnaturally high due to twisting of the specimen or tearing of the elastomer etc., had been discarded, the five highest values remaining were averaged and the average recorded as initial peel strength in pounds per inch width which values are set forth in Table I and the other tables hereafter.

Specimens to be tested for water-resistance of the adhesive bond were then immersed in an 82.degree. C. water bath for two weeks, after which they were removed, temperatures equilibrated for 30-90 minutes in water at ambient temperature and then tested for peel strength. The data obtained in these tests is presented in Table I, and it may be seen that in every case a secondary treatment of the fabric with a m-aminophenol dip resulted in substantially better peel strength; than was obtained with DAcron treated only with epoxy emulsions containing amine curative.

Two portions of emulsion containing 5% by weight of an epoxy resin (Araldite 6020, Ciba Products Co.) were prepared according to recipe I, Table I-A and diluted with water to 1000 grams containing 2% by weight resin and designated I and II.

To I was added 108 grams of a 2.5% aqueous solution of m-aminophenol as curative for the epoxy resin, i.e. 13.5 parts per hundred of epoxy resin solids. Then enough water was added to dilute the emulsion to 2000 grams and reduce the epoxy solids content to 1% by weight.

To II was added 216 grams of the 2.5% aqueous solution of m-aminophenol curative for the epoxy resin , equal to 27 parts per hundred of epoxy resin solids. Then enough water was added to dilute that emulsion to 2000 grams and reduce its epoxy solids content to 1% by weight.

A piece of Dacron fabric was dipped into emulsion I containing 13.5 phr (parts per hundred of resin by weight) of m-aminophenol and divided into four pieces and treated as follows: in example 9A a piece of the treated fabric was dried 17 hours at 27.degree. C. and cured 30 minutes at 165.degree. C.; in example 9B a piece of the fabric was treated in the same manner as 9A plus being dipped in an 0.5% by weight aqueous solution of m-aminophenol dried 17 hours at 27.degree. C. and cured 30 minutes at 165.degree. C.; in example 11A a piece of the fabric was prepared identical to 9A except the drying time was 30 minutes at 90.degree. C. Instead of 17 hours at 27.degree. C.; in example 11B a piece of the fabric was prepared identically to 11A plus being dipped in an 0.5% by weight aqueous solution of m-aminophenol dried 30 minutes at 90.degree. C. and cured 30 minutes at 165.degree. C.

Another piece of Dacron fabric was dipped into emulsion II containing 27 phr of m-aminophenol and divided into four pieces and treated as follows: in example 10A a piece of fabric was treated exactly like 9A; in example 10B a piece of the fabric was treated exactly like 9B; in example 12A a piece of the fabric was treated exactly like 11A; and in example 12B a piece of the fabric was treated exactly like 11B.

The data given in Table II shows that when Dacron is treated with an epoxy resin cured with m-aminophenol and bonded to polychloroprene the strength of such bond can be improved by further treating the dried epoxy coated Dacron by dipping in an aqueous solution of m-aminophenol and drying the resulting coating.

The eight treated fabrics prepared thus were then press-laminated to polychloroprene compound A, Table IV, in a Carver Laboratory press at 100.degree. C. and 460 psi for one minute, and the laminates were heated 20 minutes at 115.degree. C. and then heated 60 minutes in an air oven at 165.degree. C.

The strength of the fabric-elastomer bond was determined as described for example 1 through 8 heretofore and the data presented in Table II. This data shown that the peel strength of Dacron-neoprene laminates was substantially improved when Dacron fabric already treated with epoxy resin and m-aminophenol combined in an emulsion as curative therefor and at least partially cured, was given a second treatment of a 0.5 aqueous solution of m-aminophenol after such partial curing followed by drying and heat-treatment thereof. Whether the laminate after-treatment I or II was dried 17 hours at ambient temperature or 30 minutes at 90.degree. C. seemed to have little effect on the peel strength of the laminate except for examples 11A and 11B which had lower values than the corresponding examples 9A and 9B. All the "B" examples which were after-treated with m-aminophenol exhibited bonds with higher peel strength than the control or comparative "A" examples prepared without such after-treatment.

Examples 13 through 19, Table III, present a comparison of 7 epoxy resins which were employed as 1% resin solids solutions in chloroform with all but one having 10 phr of the curative methylene-bis-orthochloroaniline. The solution of the cycloaliphatic epoxy resin of example 16(a) was an exception in that this resin was dissolved in isopropanol and the 1% resin solids solution contained 10 phr tetraethylenepentamine as resin curative.

Pieces of the polyester fabric Dacron were tested with these solutions by immersion and gentle agitation for about a minute, then were dried seventeen hours at 27.degree. C. followed by curing 30 minutes at 165.degree. C. The fabrics were then each divided into two portions, one of which was cured an additional 30 minutes while the other was after-treated in a 0.5% solution of m-aninophenol and dried 16 hours at 27.degree. C. then was heated 30 minutes at 163.degree. C.

Test specimens of each of the treated fabrics were laminated to a polychloroprene compound prepared according to compound A, Table IV and tested by the method described for examples 1 through 8 above.

A description of the various epoxy resins and the peel test data obtained for the treated polyester fabrics are presented in Table III. It is noted that when the polyester fabric is treated with m-aminophenol in treatment step B the peel strength in most instances is more than doubled.

Eight epoxy resins were compared in experiments in which "Dacron" polyester fabric (see examples 20 through 27 of Table III-A), was first soaked for about a minute in a 0.5% solution of the particular resin in chloroform or trichlorethylene, then was dried at about 27.degree. C. until the solvent had evaporated. The fabric was then cured for one hour in a 165.degree. C. air oven.

Each of the epoxy-treated fabrics was then dipped into a 0.5% aqueous solution of m-aminophenol, after which it was dried at about 27.degree. C. for about 16 hours followed by heating for 30 minutes at 165.degree. C.

The adhesion of these treated fabrics to polychloroprene was evaluated by preparing test laminates of the fabrics with a polychloroprene compound (see compound A, Table IV) as described above, and determining the peel strength of specimens cut from the cured laminates. The data obtained from these tests is presented in Table III-A. This table teaches it is unnecessary to coat the polyester fabric with an epoxy resin which contains curative as the epoxy resin can be cured or partially cured to the fabric with heat alone and without curative being present with the epoxy resin.

Examples 28 through 35 Table V are derived from an experiment with a single piece each of cotton and nylon 66 fabric were first treated by dipping them into an emulsion prepared according to recipe I, Table I-A and containing 1% by weight solids of a diglycidyl either of bisphenol A (Araldite 6020) and 10 phr of the epoxy curative mthylene-bis-orthochloroaniline. The fabrics were gently agitated in this emulsion for about a minute and then hung up at room temperature (about 27.degree. C.) for about 16 hours, and then were heated 60 minutes at 165.degree. C. in an air oven to at least partially cure the epoxy resin upon the fibers of the fabric.

The treated cotton and nylon fabrics were then each divided into four pieces, the first of which was reserved for testing without further treatment, while the other three were variously after-treated. The second piece of each was after-treated by dipping it into a 0.5% aqueous solution of m-aminophenol, after which it was dried 16 hours at about 27.degree. C. and then was heated about 30 minutes at 165.degree. C. in an air oven.

The third piece of cotton and nylon fabric was after-treated in a RF dip of 1% resin solids which was aged about 21/2 hours before use. The fourth piece was after-treated by dipping in a mixture of equal parts by weight of a portion of the same RF dip (aged about 21/2 hours) and of a 1% solution of aminophenol and dried 16 hours at 165.degree. C.

The resorcinol-formaldehyde referred to as RF resin was made with a 1:2 molar proportion of resorcinol to formaldehyde, and sodium hydroxide was employed as a catalyst in the amount of 5% based on the dry solids weight of the RF resin, and the resin was diluted with water to 1% by weight concentration.

The four pieces each of variously treated cotton and nylon fabric were then laminated to a polychloroprene compound A of Table IV and test specimens were cut from the laminates after they were cured. The improved adhesion provided by these after-treatments is shown in the peel strength data of Table V.

The peel strength data in Table V teaches that cotton fabric and nylon fabric polychloroprene laminates show beneficial increase in peel strength in the same manner as polyester fabric when either the fabric with epoxy resin coating alone or the fabric with epoxy resin coating plus resorcinol-formaldehyde coating overlay is after-treated with aqueous m-aninophenol.

Examples 36 through 41 Table VI are concerned with the adhesion of glass fiber fabric to a polychloroprene. Glass fiber fabric was first coated with an epoxy resin which was cured and then after-treated with m-aminophenol (both alone and in combination with resorcinol-formaldehyde dip) and the adhesion to polychloroprene determined.

The glass fiber fabric was cleaned thoroughly in a sodium dichromate acid cleaning bath (see footnote to Table VI) followed by rinsing in plain water and dried. The fabric was then treated in a chloroform solution containing 1% diglycidyl ether of bisphenol A resin and 10 phr of the epoxy resin curative methylene-bis-orthochloroaniline. The fabric was agitated gently in this solution for about a minute, then dried four hours at 27.degree. C., and finally heated 60 minutes at 163.degree. C. to at least partially cure the epoxy resin on the glass fibers.

A portion of this treated fabric was then aftertreated by dipping in a 0.5% by weight aqueous solution of m-aminophenol after which it was dried 16 hours at 27.degree. C. followed by heating 30 minutes at 163.degree. C.

Two portions each were then cut from both the pieces of glass fiber fabric that had been coated only with the epoxy coating and that which had been also after-treated with m-aminophenol. One portion of each of these fabrics was treated in a 1% alkaline RF dip (as in Examples 21 through 28) while the other was treated in a dip containing equal parts by weight of the 1% RF dispersion and a 1% solution of m-aminophenol (as in the examples of Table V). These fabrics were dried 16 hours at 27.degree. C. and then heated 10 minutes at 115.degree. C. before test specimens were made by lamination with a polychloroprene compound of Table IV, curing and testing for peel strength of the laminate as described for Examples 1 through 8 above in the section on "Preparation and Testing of Specimens." Table VI presents the peel test data obtained in this experiment which again teaches the beneficial effect of after-treatment of the coated glass fabric with m-aminophenol to improve the peel strength of the glass fabric-elastomer laminates.

Examples 42 and 43 are derived from an experiment in which six different afterdips containing m-aminophenol aqueous solution, resorcinol-formaldehyde resin dispersions, and various combination of these dips were applied to six portions each of two polyester fabrics that had been first treated with epoxy resin emulsion.

In Example 42 a piece of the polyester fabric Dacron was first dipped into an emulsion containing 1% DGEBA* resin solids prepared according to recipe I, Table I-A and described under Examples 1 thru 8 above in the section on "Preparation of Epoxy Emulsions." The fabric was then dried 16 hours at 27.degree. C. followed by curing 30 minutes at 165.degree. C.

In Example 43, a portion of polyester fabric was treated in an epoxy emulsion identical with that of Example 42 except that in addition to its 1% epoxy resin solids it also contained 10 phr of the epoxy resin curative methylene-bis-orthochloroaniline. After the fabric was dipped into the epoxy emulsion with gentle agitation for about a minute it was dried 16 hours followed by curing 30 minutes in an air oven at 165.degree. C. and then was divided into six portions and dipped as described hereafter.

The six dips used in after-treating the six portions each of the two fabrics of Examples 42 and 43 were as follows:

(1) An alkaline RF dip containing 1% RF resin solids and in which the molar ratio of resorcinol to formaldehyde was 1 to 1.5. Sodium hydroxide was employed as catalyst in the amount of 5.5 parts per hundred resin solids. The dispersion was made as a 2% stock aqueous solution and aged 2 hours before it was diluted to 1% and then was aged 1 more hour before use.

(2) A resin dispersion prepared like dip No. (1) except that half of the resorcinol was replaced with m-aminophenol. This resulted in an opaque dispersion of partially particulate resin.

(3) A resin dispersion prepared like dip No. (1) above except that all of the resorcinol was replaced with m-aminophenol. The dispersion was opaque yellow and was aged 2 1/2 hours before use, at which time an examination of a portion of the dispersion under a microscope showed that the resin was present as spherical particles which were less than a micron in diameter and exhibited Brownian movement.

(4) A resin dip prepared from half of the 2% stock dispersion of RF resin of dip No. (1) (aged 2 hours) by adding to it an equal weight of m-aminophenol solution in which the weight of m-aminophenol equalled the weight of resorcinol.

(5) A resin dip prepared from half of the 2% stock dispersion of dip No. (2) (aged 2 hours) by adding to it an equal weight of aqueous solution of m-aminophenol in which the weight of m-aminophenol equalled the combined weights of resorcinol and m-aminophenol in the resin of dip No. (2).

(6) A resin dip prepared from half of the 2% stock dispersion of dip No. (3) (aged 2 hours) by adding to it an equal weight of aqueous m-aminophenol solution in which the weight of m-aminophenol was equal to the weight of the m-aminophenol in the m-aminophenol-formaldehyde resin of dip No. (3).

The twelve pieces of polyester fabric treated by dipping in the six dispersions described above were dried about 16 hours at 27.degree. C. Adhesion test specimens were then prepared by laminating the fabrics to a polychloroprene compound A, Table IV, by curing the laminates 60 minutes at 165.degree. C. and then cutting test specimens from it as described for Examples 1 through 8 in the section above on "Preparation and Testing of Specimens." Peel test data obtained in these tests is presented in Table VII.

From the data in Table VII the following conclusions can be drawn:

(1) If the fabric is only coated with an epoxy resin then after-treatment with m-aminophenol will greatly enhance the bonding to elastomers;

(2) If the fabric is treated with

(a) an epoxy resin and with

(b) a phenoplast of the type of resorcinolformaldehyde, resorcinol-m-aminophenolformaldehyde or m-aminophenol-formaldehyde then the adhesion to elastomers is greatly enhance by treating with m-aminophenol either between the epoxy coating and the phenoplast coating or after the phenoplast coating.

The m-aminophenol to form a dip thereof may be added to the aqueous RF resin or RFL resin before drying thereof, and preferably the aqueous RF or RFL resin is essentially free of formaldehyde to avoid having such formaldehyde react with the m-aminophenol and convert it to resin, which conversion could render the m-aminophenol ineffective for the purposes of this invention.

Examples 44 and 45 are concerned with the adhesion of an SBR compound to a fabric woven from modified polyester fibers produced by the Celanese Corporation, and show the improved adhesion resulting from the addition of m-aminophenol to RFL dips used in treating this fabric.

The fabric was an "adhesive activated" 12.8 oz. woven fabric containing Celanese type 790 yarn in the warp, and 797 (low shrinkage equivalent) yarn in the filling.

In Example 44, Table VIII an RFL dip was made as follows: 33.2 parts by weight resorcinol was dissolved in a solution of 2.6 parts sodium hydroxide in 665 parts water and then 34.4 parts 37.5% formalin was added to provide a proportion of 1.4 formaldehyde to 1 resorcinol. This dispersion was aged 1 1/2 hours and then combined with a mixture of 390 parts by weight of a butadiene-styrene-vinylpyridine-latex (Gen-Tac latex, a trademark product of the General Tire and Rubber Co.) of 41% solids and 30 parts of an SBR latex (Pliolite 3757E latex, a trademark product of the Goodyear Tire and Rubber Co.) of 66% solids plus 70 parts water. This RFL dip was aged 24 hours before use.

The RFL dip used in Example 44B was made from a portion of that dip from Example 44A by adding to it m-aminophenol in an amount equal to the weight of resorcinol in the RFL dip and dissolved in water equal to 1/2 the weight of RFL dip. The m-aminophenol can advantageously be combined with the elastomer latex especially with the butadiene-styrene-vinylpyridine latex (Gen-Tac latex).

The RFL dip of Example 45A was prepared as follows: 11 parts resorcinol were added to a solution of 1.5 parts sodium hydroxide in 239 parts water, and then 16.2 parts 37.5% formalin were added to provide a proportion of 2 moles formaldehyde to 1 mole resorcinol. This dispersion was aged 2 1/2 hours at about 27.degree. C. and then added to a mixture of 86 parts polychloroprene latex (Neoprene 635 latex, a trademark product of E. I. du Pont de Nemours & Co. Inc.) of 58% solids. This RFL dip was aged 1 hour before use.

The RFL dip of Example 45B was prepared from a portion of that 45A by adding to it m-aminophenol equal in weight to the resorcinol of the RFL dip and dissolved in water equal in weight to 1/2 that of the RFL dip.

Portions of that modified polyester fabric were dipped in each of the four RFL dips described above and then dried at least 16 hours at 27.degree. C. Test specimens were then prepared by laminating them to an SBR compound (See Table VIII by the method described under Examples 1 through 8 above in the section on "Preparation and Testing of Specimens." Peel strength test data obtained for these four treated fabrics is presented in Table VIII.

The data in Table VIII shows that when adhering polyester fabric to butadiene-styrene-vinylpyridine elastomers employing a resorcinol-formaldehyde-latex dip the addition of m-aminophenol to the dip improved the adhesion of the laminate.

Examples 46 and 47 are concerned with the adhesion to a polychloroprene compound of the polyester Dacron and nylon 66 fabrics both of which were treated with aqueous dips containing equal parts by weight of an emulsified epoxy resin and an acidic RF resin in aqueous dispersion while portions of each were after-treated with m-aminophenol in aqueous solution.

The acidic RF resin dispersion was prepared as follows: 6.4 parts by weight resorcinol was dissolved in a solution of 1 part alkylarylpolyether alcohol (Triton X-155, a trademark product of Rohm and Haas Co.) and 30 parts of a 1% aqueous solution of hydrochloric acid were added followed by 9.4 parts 37.5% formalin. This mixture in a jar was rotated end-over-end for four hours, at the end of which time the RF resin was slightly milky in appearance. It was diluted to 1% resin solids with water and was then added to an equal weight of a 1% resin solids emulsion of a cycloaliphatic epoxy resin (Unox Epoxy 221, a trademark product of Union Carbide Co.).

In Examples 46A and 47A, pieces of polyester and nylon fabrics respectively were each treated by immersion and gentle agitation for about one minute in the epoxy-RF dip described above and then were dried 16 hours at 27.degree. C. followed by curing 30 minutes at 165.degree. C. In Examples 46B and 47B portions of these fabrics were then after-treated by dipping in 0.5% aqueous solutions of m-aminophenol after which they were dried 16 hours at 27.degree. C. followed by curing 30 minutes at 165.degree. C.

Adhesive test specimens were prepared from the above four fabrics by lamination with a polychloroprene compound A, Table IV, as described for Examples 1 through 8 in the section of "Preparation and Testing of Specimens." Peel strength test data for these treated fabrics is presented in Table IX. When the aqueous epoxy emulsion and the resorcinol-formaldehyde aqueous dispersion are combined in a single dip which is cured on the fibrous material to provide adhesion to rubber, then there is an advantage in treating the fabric first with the combination dip and drying the same and then with an aqueous m-aminophenol dip which in turn is dried in order to promote or improve the strength of the bond obtained.

Examples 48 through 51 concern the adhesion of polyester fabric, Dacron, to an SBR compound and presents a comparison of the effects of after-treatments of the fabric with RFL dips both with and without the addition of m-aminophenol.

In Examples 48 and 49 the polyester fabric was first treated by dipping in a 0.5% chloroform solution of a DGEBA resin (Araldite 6020), then was dried 4 hours at 27.degree. C. and cured 30 minutes at 165.degree. C. after which it was treated in Example 49 with 0.5% aqueous m-aminophenol solution, was dried 16 hours at 27.degree. C., and cured 30 minutes at 165.degree. C. The fabrics were then cut into two portions, one of which was treated with RFL dip while the other was treated with a portion of the same RFL dip plus m-aminophenol equal in weight to the resorcinol of the dip. The recipe for the RFL dip of Example 44 is given in footnote (1) of Table VIII.

In Example 50 a piece of polyester fabric was first treated with an emulsion containing 1% epoxy resin solids (Araldite 6020) and 16 phr m-aminophenol. The fabric was dried 16 hours at 27.degree. C. and then cured 60 minutes at 165.degree. C. The fabric was then divided into two portions, one of which (Example 50A) was treated with the RFL dip described in footnote (1) Table VIII while the other (Example 50B) was treated with the same RFL dip plus m-aminophenol equal in weight to the resorcinol of the RFL dip.

In Example 51 the polyester fabric was treated with a 1% solution of a DGEBA resin in chloroform containing also 10 phr methylene-bis-orthochloroaniline, after which it was dried 2 hours at 27.degree. C. followed by curing 60 minutes at 165.degree. C. The fabric was then divided into 2 pieces; fabric designated 51A was treated in the RFL dip described in footnote (1) of Table VIII while the other fabric, 51B, was treated in a portion of the same dip to which was added m-aminophenol equal in weight to the resorcinol of the RFL dip.

These fabrics, after treatment with RFL dips, were dried 16 hours at 27.degree. C. and then test specimens were prepared from laminate of the fabrics with an SBR compound (see Table X), by the method described for Examples 1 to 8 above in the section on "Preparation and Testing of Specimens." Peel test data for these variously treated fabrics is presented in Table X.

The data in Table X shows the adhesion of Dacron to SBR, employing epoxy coatings at least in part cured to the Dacron with heat and with or without the aid of curative material and with a further coating of RFL dip dried thereon, and improved by applying m-aminophenol prior to the RFL dip or in admixture with the RFL dip and drying the same before assembly with the vulcanizable elastomer and vulcanization thereof.

Example 52 is concerned with the adhesion of the polyester fabric Dacron to a polychloroprene compound and demonstrates the effect of a m-aminophenol aqueous dip as an after-treatment applied to fabric previously treated with an aqueous dip containing epoxy resin, m-aminophenol, RF resin, and an elastomer latex and cured. The aqueous epoxy-RFL dip was prepared as follows:

First an RF resin dispersion was prepared by dissolving 3.2 parts by weight resorcinol in 25 parts 1% aqueous solution of sodium hydroxide and adding to this 4.7 parts 37.5% formalin. This was allowed to age for 2 hours at about 27.degree. C. and then it was diluted with water to form a 1% dispersion.

To the RF resin dispersion was added 12.2 parts by weight of a butadiene-styrene-vinylpyridine terpolymer latex (Gen-Tac) diluted with water to contain 5 parts solids and also an emulsion containing 1% DGEBA resin solids (Araldite 6020) and m-aminophenol in the amount of 16 parts by weight per hundred parts epoxy resin.

Polyester fabric was treated in this dip by immersion and gentle agitation for about a minute, then was dried 16 hours at about 27.degree. C. followed by heating 60 minutes at 165.degree. C. A portion of this fabric (Example 52A) was then reserved for testing while the balance (Example 52B) was dipped into a 0.5% aqueous m-aminophenol solution and dried 16 hours at 27.degree. C.

These two fabrics were each laminated to a polychloroprene compound A, Table IV, and test specimens cut from the cured laminates as described for Examples 1 through 8 above in the section of "Preparation and Testing of Specimens." The comparative peel strength test data for these two treated fabrics is reported in Table XI.

The data in Table XI shows that the bond between Dacron and Neoprene, adhered with the aid of an aqueous emulsion of epoxy resin and resorcinol-formaldehyde resin containing m-aminophenol of at least partially cured on the Dacron before assembly with the Neoprene and vulcanization thereof, is improved by an after-treatment with m-amino-phenol dried thereon prior to the assembly with the Neoprene and vulcanization thereof.

Examples 53 and 54 are concerned with the adhesion of nylon 66 fabric to polychloroprene and demonstrate the effect of m-aminophenol after-treatment on nylon treated with RF resin in the form of particles of greater than colloidal size.

In Example 53 an RF resin was prepared using an acid catalyst as follows: 6.4 parts by weight resorcinol was dissolved in 70 parts water and then 30 parts 1% aqueous hydrochloric acid was added followed by 9.4 parts 37.5% formalin. This solution was allowed to stand at about 27.degree. C. for one hour and 40 minutes, by which time an off-white precipitate (slightly pink) had formed in the bottom of the beaker containing the solution. The dispersion including precipitate were put into a small blender and run at high speed for about five minutes to break up the soft RF precipitate. Examination of a sample of the dispersion under a microscope then showed the resin to be present in the form of irregular spherical particles ranging in size from 3 to 11 microns in diameter with the majority in the 4-8 micron size range. When dry the spheres were bright red. This RF dispersion was diluted with water so that the resin solids were reduced to 1% by weight. One piece of nylon fabric was dipped into the dispersion described above and then dried overnight at 27.degree. C. (Example 53A). Then a portion of this fabric was cut off, dipped into a 0.5% aqueous solution of m-aminophenol, and dried 16 hours at 27.degree. C. (Example 53B).

The RF resin of Examples 54A and 54B was prepared as follows: 6.4 parts by weight resorcinol was dissolved in a solution of 1 part triethanolamine and 100 parts water and then 9.4 parts formaldehyde were added, and the mixture was ball-milled in a glass container for 21/2 hours. The dispersion was then opaque and a pale pink in color. When a sample of the dispersion was examined under a microscope it was seen that the resin was in the form of regular spherical globules in the range of 1.5 to 3.5 microns in diameter and exhibiting Brownian movement. This dispersion was diluted with 883 parts water to reduce the RF solids to 1%.

A piece of nylon fabric was treated in the above dispersion by immersion and gentle agitation for about a minute. Then it was dried 16 hours at 27.degree. C. (Example 54A). A portion of it was then cut off and after-treated with a 0.5% aqueous solution of m-aminophenol (Example 54B) and dried again 16 hours at 27.degree. C.

The four pieces of treated nylon fabric were then tested in laminates with a polychloroprene compound A, Table IV, according to the procedure described for Examples 1 through 8 above in the section on "Method of Testing the Strength of Fabric-Elastomer Bonds". The results of the peel strength tests are presented in Table XII.

The results set forth in Table XII show that adhering nylon to Neoprene using a particulate RF dip is improved when the nylon is given an after dip with aqueous m-aminophenol. We have found that the particulate RF dip here referred to when used as adhesives provides fibrous material-elastomer laminates having reduced stiffness as compared with laminates employing conventional RF and RFL dips.

Examples 55 and 56 demonstrates the effects of the addition of varying amounts of m-aminophenol to elastomer latices used in RFL dips for the treatment of polyester fabric to improve its adhesion to elastomer compounds.

The particular polyester fabric used in these examples was woven from the "adhesive activated" types 790 and 797 polyester yarns produced by Celanese Corporation.

The latex to which the m-aminophenol was added was a mixture of a butadiene-vinylpyridine-styrene terpolymer latex (Gen-Tac latex, General Tire and Rubber Company) and an SBR latex (Pliolite 3757E, Goodyear Tire and Rubber Co.) in the ratio of 5 parts vinylpyridine-terpolymer latex solids to 1 part SBR latex solids. The m-aminophenol was added to the butadiene-vinylpyridine-styrene-latex.

This mixture of latices was divided into four portions of 150 g., each containing 60 g. solids. To the first (control) portion 100 g. pure water was added, while to the second portion 3 g. m-aminophenol dissolved in 97 g. water were added. Similarly to the third portion were added 6 g. m-aminophenol dissolved in 94 g. water, and to the fourth portion 12 g. m-aminophenol dissolved in 88 g. water. These latex mixtures were allowed to stand for 11/2 hours before 150 g. of an alkaline RF dispersion containing 12 g. RF resin solids (of 1:2 resorcinol-formaldehyde molar ratio) were added to each. This RF resin dispersion had been aged 11/2 hours before addition to the latex mixture. The RFL mixture thus obtained was aged for 1 hour before treatment of the polyester fabric by dipping pieces of it into each of the four RFL dips, respectively.

The four treated polyester fabrics were hung up to dry at room temperature overnight then were heated 10 minutes at 115.degree. C. They were then formed into laminates with an SBR compound in a Carver press and then the laminates were cured 60 minutes at 165.degree. C. and specimens were cut from the cured laminates and were tested for peel strength. The results of these tests are presented in Table XIII and show that for bonding a fabric material to an elastomer using an RFL dip, when m-aminophenol is added to the elastomer latex which is combined with an aqueous dispersion of a resorcinol-formaldehyde resin then better adhesion is obtained than when the elastomer latex of such RFL dip does not contain added m-aminophenol.

Similarly, in practicing Example 45B, the m-aminophenol may be added to one or more of the elastomer latices, e.g. the polychloroprene latex, the butadiene-styrene latex, and the butadiene-styrene-vinylpyridine latex, and the thus improved latex composition can be used in forming the improved RFL dip. Preferably the m-aminophenol is combined with the vinylpyridine polymer latex, in the ratio of about 10 parts m-aminophenol per 15 parts latex, dry basis, and this combination used in the proportions set out in Example 45B provides the designated quantity of m-aminophenol based on the RF resin.

Examples 57 and 58 demonstrate the improved adhesion between polyester and an SBR compound obtained by adding m-aminophenol to the second dip of a 2-dip commercial type fabric treatment in which the first dip was a dispersion containing a blocked diisocyanate and an epoxy resin, while the second was an RFL dip containing vinylpyridine terpolymer latex.

A 40% dispersion of the blocked diisocyanate was first prepared by ball-milling overnight a mixture of 10 parts of the bis phenol adduct of methylene-bis(4-phenyl isocyanate) (Hylene MP, E. I. du Pont de Nemours & Co. Inc.) and 1 part of sulfonated ester of a fatty acid (Aerosol OT, American Cyanamid Co.) dissolved in 14 parts water.

In the blender was combined 9 parts of the Hylene MP dispersion containing 3.6 parts of the dry blocked diisocyanate, 4 parts of a 1% aqueous solution of gum tragacanth and 1.36 parts of a water dispersible dry epoxy resing (Epon 812) and 86 parts water and agitated to form a dispersion.

"Dacron" polyester fabric was dipped into the above dispersion and dried 6 hours at about 27.degree. C. followed by heating 5 minutes at 115.degree. C. This treated fabric was then divided into two pieces, one of which (Example 57) was dipped into a 20% solids RFL dip while the other (Example 58) was dipped into a second portion of the same RFL to which had been added 5 parts by weight m-aminophenol per 8.5 parts RF resin.

The basic RFL dip of these examples was prepared as follows: 11 parts by weight resorcinol was combined with 320.5 parts water, 0.3 parts sodium hydroxide, and 16.2 parts 37% formalin and this mixture was allowed to age for six hours before combination with 250 parts 40% vinylpyridine terpolymer latex (Gen-Tac, General Tire and Rubber Co.) and 11.3 parts 28% ammonium hydroxide. This dip was divided in half and to one half 5 parts m-aminophenol dissolved in 100 parts water were added.

Pieces of polyester fabric, pre-treated as described above were dipped into each of the above RFL dips, dried 17 hours at about 27.degree. C. and then heated 30 minutes at 165.degree. C. before being formed into test laminates with an SER compound.

Table XIV presents test data for the cured laminates showing that m-aminophenol added to the RFL dip contributed a significant increase in peel strength.

Examples 59 and 60 demonstrate the effect on adhesion of adding m-aminophenol to RFL dispersions in which the RF resin was made in the presence of the latex (Gen-Tac, a vinylpyridine terpolymer latex produced by General Tire and Rubber Co.). This RFL dip was prepared as follows: 11 parts resorcinol was dissolved in a solution of 0.3 parts sodium hydroxide in 130 parts water and added to 250 parts Gen-Tac latex containing about 100 parts polymer solids then was added 16.3 parts 37% formaline in 191 parts water and the mixture was aged at 27.degree. C. for 21/2 hours. Then 11.3 parts 28% ammonium hydroxide was added and the dispersion was allowed to stand for another half hour before use.

The RFL dispersion was then divided into two equal portions each containing 8.5 parts RF resin. To one portion (Example 59) was added 100 parts by weight water and to the second portion of the dispersion (Example 6) was added a solution of 5 parts m-aminophenol in 95 parts water.

Pieces of modified polyester fabric (woven of Celanese Corporation's types 790 and 797 yarns) were immersed in the above RFL dips and then dried at about 27.degree. C. for 16 hours followed by heating 10 minutes at 115.degree. C.

The 2 pieces of RFL treated polyester fabric were then each formed into test laminates with sheets of an SBR compound.sup.(1) and the laminates pre-heated 20 minutes at 115.degree. C. then cured 60 minutes at 165.degree. C. Table XV presents test data showing that the addition of m-aminophenol resulted in a considerable improvement in adhesion.

Examples 61 and 62 are concerned with the adhesion of nylon fabric to a fluoroelastomer compound and demonstrate improvement of adhesion resulting from the addition of m-aminophenol to RF fabric dips.

An RF resin dispersion was first prepared by combining 6.4 parts resorcinol, 100 parts water, 0.5 parts sodium hydroxide and 9.5 parts 37% formalin. This was aged for 21/2 hours at about 27.degree. C. then diluted with water to provide a 2% dispersion of RF resin solids. In Example 61, 100 parts of this 2% dispersion were diluted with an equal weight of water and a piece of nylon 66 fabric was dipped into the resultant 1% dispersion and then dried at about 27.degree. C. for 16 hours. In Example 62, to 100 parts of the 2% dispersion was added an equal weight of a 2% aqueous solution of m-aminophenol. A piece of nylon fabric was similarly dipped into this mixture and dried.

Laminates were prepared from these two pieces of treated nylon and a compound of an elastomeric copolymer of vinylidene fluoride and perfluoropropylene (Viton B, E. I. du Pont de Nemours and Co. Inc.). Table XVI presents the peel test data obtained from test specimens cut from the cured laminates.

Examples 63-93 are directed to further embodiments of the invention wherein the applicant's discovery is applied to the improvement of adhesive bonds with combinations of substrate other than those set out in Examples 1-62, and with Examples 1-62 illustrate the general applicability of the invention to the improvement of phenoplast adhesives, for adhering wood, metal, plastics, glass, rubber, paper, etc., substrates to like or different substrates.

A mill-mixed polychloroprene masterbatch consisting of 100 parts Neoprene AC (E. I. du Pont de Nemours & Co. Inc.), 2 parts phenyl-alpha-napthylamine, 4 parts magnesium oxide, and 5 parts zinc oxide was added to a solution of 45 parts heat reactive phenolic resin (Bakelite CKM-1634, Union Carbide Corporation) dissolved in 431 parts toluene. Four additional parts magnesium oxide were also added and the mixture was ball-milled for 24 hours, then one part water was added and the cement was ball-milled for another hour.

The cement was then divided into three separate portions each containing 33.3 parts rubber and 15 parts resins. To the first portion (Example 63) were added 32 parts methyl ethyl ketone (MEK). To the second portion (Example 64) was added a solution of 11 parts m-aminophenol dissolved in 44 parts MEK, while to the third (Example 65) was added 22.5 parts m-aminophenol dissolved in 90 parts MEK. After these additions, the cements were again ball-milled for an hour before use.

The three cements were each applied with a brush to 3/8 inch square areas near one end of flat soft-wood sticks. The first coat of cement was allowed to dry for about an hour, than second coats were applied and when they had become tacky pairs of sticks were assembled together, with cement-coated areas together and the uncoated ends of the sticks forming a 180.degree. angle. The sticks were pressed together with finger pressure and then were placed under weights for about 17 hours with one 500 g. weight supported by 2 specimens lying side by side. The weights were then removed, and the specimens left to age at about 27.degree. C.

Table XVIII presents data obtained in lap shear tensile tests of these specimens and demonstrates the improvement of adhesive strength obtained by the addition of m-aminophenol to the polychloroprene-phenolic cement.

Examples 69 and 70 are concerned with supported adhesive films prepared by dipping filter paper into RFL dips containing vinylpyridine terpolymer latex, and demonstrate the improved adhesion obtained by after-treating the dried films by dipping them into a dilute solution of m-aminophenol.

The RFL dip was prepared as follows: 12.8 parts resorcinol were dissolved in 100 parts aqueous 1% sodium hydroxide, and then 19 parts 37% formalin were added. This mixture was aged for 30 minutes and then 250 parts Gen-Tac latex (General Tire and Rubber Co.) were added to it and the combination was aged for two hours before use. Strips of filter paper were then dipped into the RFL dip and dried at about 27.degree. C. After about 24 hours one of the strips was dipped into a 0.5% solution of m-aminophenol in MEK and re-dried.

After 3 days, circles 3/16 inch in diameter were cut from the two films and each circle was placed between the over-lapping ends of two flat sticks 1/4 inch wide so that the circle was at about the midpoint of the one inch overlap. This assembly was wrapped in aluminum foil to hold its members temporarily in place and then was laminated in a small laboratory (Carver) press for one hour at a temperature of 160.degree. C.

In Example 69 and 70, the films were those without and with the m-aminophenol after-dip respectively. The results of lap shear tensile tests conducted as in Examples 63-68 and presented in Table XVIII showed that after-treatment with m-aminophenol resulted in improved adhesion.

In Examples 71 through 74 an RFL adhesive dip containing polychloroprene latex was absorbed on both paper and nylon fabric supports and dried, after which portions of the treated paper and fabric were further treated by being dipped into dilute solutions of m-aminophenol.

The basic RFL dip was prepared as follows: 12.8 parts resorcinol were dissolved in 100 parts aqueous sodium hydroxide and then 19 parts 37% formalin were added. The solution was aged 30 minutes and then added to 172 parts Neoprene 635 latex (E. I. du Pont de Nemours & Co. Inc.) containing 100 parts solids. After this mixture had aged for two hours, a strip of filter paper and a strip of nylon fabric were each dipped into it and dried at about 27.degree. C. These furnished the tapes for Examples 71 and 73. Portions of the treated paper and fabric were then dipped into a 0.5% solution of m-aminophenol in MEK and re-dried. Those furnished the tapes for Examples 72 and 74.

In Examples 71 and 72, 1/2 inch squares were cut from the paper-supported adhesive tapes and placed between the overlapping ends of 1/2.times.3.times.3/64 inch aluminum strips. These assemblies were laminated in a press for 60 minutes at 165.degree. C.

In Examples 73 and 74, circles 3/16 inch in diameter were cut from the nylon fabric-supported adhesive tapes and the circles were placed between the over-lapped ends of 1/4 inch wide flat wood sticks, and these assemblies were also press-laminated 60 minutes at 165.degree. C.

The four specimens described above were subjected to lap shear tensile tests as described for Examples 63 to 68. The results of these tests are presented in Table XIX and show that where the paper and nylon tapes were after-treated with m-aminophenol (Examples 72 and 74) adhesion was improved in both instances.

Examples 75-78 demonstrate improvement of wood-to-wood adhesion resulting from the addition of m-aminophenol to a polychloroprene-phenolic cement used in preparing adhesive films supported on nylon film and aluminum foil.

A mill-mixed polychloroprene masterbatch containing 100 parts Neoprene AC (E. I. du Pont de Nemours & Co. Inc.) 2 parts phenylalpha-napthylamine, 4 parts magnesium oxide, and 5 parts zinc oxide was dissolved in 360 parts toluene. To this was added a combination of 50 parts modified Novolac resin (Durex 12686, Hooker Chemical Corporation ) dissolved in an equal weight of acetone and 41 parts hexamethylenetetramine dissolved in 47 parts chloroform. The cement was then divided into two equal portions, to the first of which (Examples 75 and 77) was added 50 parts acetone while to the second (Examples 76 and 78) m-aminophenol in 37.5 parts acetone.

The cement containing m-aminophenol and that without it were each applied with a brush to both nylon 6 film (Examples 75 and 76) and to aluminum foil of 1 mil thickness (Examples 77 and 78) and the coatings were allowed to dry thoroughly at about 27.degree. C.

Circles of 1/16 inch diameter were then cut with a cork borer from the coated nylon films and aluminum foils, and were placed between the overlapping ends of soft-wood sticks so that the circles of adhesive tape were about in the center of a one inch overlap of the sticks. Aluminum foil was wrapped around these assemblies to hold their members temporarily in place and then they were laminated together in a small laboratory press (Fred S. Carver Inc.) for 60 minutes at 160.degree. C. (Examples 75 and 76) or 55 minutes at 180.degree. C. (Examples 77 and 78) and a pressure of at least 40 psi, sufficient to insure good contact.

The cured adhesive specimens, after cooling, were tested for lap shear strength as previously described for Examples 63-68. The results, as presented in Table XX, showed that the specimens of Examples 76 and 78, laminated with supported phenolic-polychloroprene adhesive containing m-aminophenol were superior in lap shear strength to those of 75 and 77 in which m-aminophenol was not used.

Examples 79-82 are concerned with the adhesion of wood to wood by the use of paper tapes saturated with a combination of thermosetting resorcinol-formaldehyde resin and either vinylpyridine terpolymer elastomer (Examples 79 and 80) or butadiene-acrylonitrile elastomer (Examples 81 and 82) and show the increase of adhesive strength contributed by an after-treatment of these tapes with m-aminophenol applied from a dilute solution.

The adhesive tapes were prepared as follows: 19.4 parts Penocolite R-2170 (a 75% aqueous solution of resorcinol formaldehyde thermoplastic resin, Koppers Co. Inc.) were diluted with 120 parts 1% aqueous sodium hydroxide, and then 2.4 parts hexamethylenetetramine dissolved in 158 parts water were added. This solution was then divided into 2 equal portions, to one of which 125 parts (50 parts solids) Gen-Tac Latex (General Tire and Rubber Co.) were added, while to the other were added 117 parts (50 parts solids) Chemigum 245-CH5 (butadiene-acrylonitrile latex, Goodyear Tire and Rubber Co.).

Strips of filter paper were dipped into each of these resin-latex mixtures, and were thoroughly dried at about 27.degree. C. Then portions of each were dipped into a 0.5% solution of m-aminophenol in acetone, after which they were again dried as before.

The tapes coated with adhesives containing vinylpyridine terpolymer and butadiene-acrylonitrile elastomer and not after-treated were used in Examples 79 and 81 respectively, while portions of these tapes which were after-treated with m-aminophenol were used in Examples 80 and 82.

Circles of 1/16 inch diameter were cut from these tapes and placed between the over-lapping ends of flat wood sticks so that the circles of adhesive tape were approximately in the center of a one inch over-lap of the sticks. These assemblies were then wrapped in aluminum foil to hold their members temporarily in place and then were laminated in a small laboratory press for 60 minutes at 160.degree. C. and a pressure of at least 50 psi, sufficient to insure good contact.

After cooling, the specimens were tested for lap shear tensile strength as described for Examples 63068. The results of these tests, as presented in Table XXI, showed that after-treatment of the tapes with m-aminophenol resulted in improved adhesion.

Examples 83-85 are concerned with phenolic-polyamide-polychloroprene adhesives on paper tape support, and demonstrate the improvement of wood-to-wood adhesion by the addition of m-aminophenol to the cements used in preparing the tapes. They also demonstrate that acidifying the cement (in Examples 85) did not destroy the effectiveness of m-aminophenol.

In Example 83, four parts of a thermoplastic phenolic resin (Durex 22193, Hooker Chemical Corp.) and four parts polyamide resin (Versamid 115, General Mills Inc.) were dissolved in 32 parts toluene and then 24 parts of a 25% solution of polychloroprene (Neoprene AC, E. I. du Pont de Nemours & Co. Inc.) were added.

To a portion of the cement of Example 83 m-aminophenol was added in the amount of 50 parts per hundred phenolic resin. This cement was used in Example 84.

The cement of Example 83 was prepared by adding to a portion of that of Example 84 glacial acetic acid in the amount of 50 parts per hundred phenolic resin, which was sufficient to render the solution definitely acid (about pH 5.0).

Each of the above cements was applied with a brush to both sides of a strip of filter paper, with one side being allowed to dry before the strip was turned over for the painting of the other side. When both sides of the strips of paper tape were thoroughly dry, 3/16" diameter circles were cut from them with a cork borer and placed between the over-lapping ends of flat wood sticks so that the circles of adhesive tape were approximately in the center of a one inch over-lap of the sticks. These assemblies were wrapped in aluminum foil to hold their members temporarily in place and then were laminated in a small laboratory press for 30 minutes at 160.degree. C., after which the heat was shut off and the specimens were cooled under pressure sufficient to insure good contact (in excess of 60 psi) to about 80.degree. C. before removal from the press.

After cooling, the specimens were tested for lap shear tensile strength as described for Examples 63-68. The data obtained in these tests, as presented in Table XXII, showed that the addition of m-aminophenol resulted in improved wood-to-wood adhesion.

Examples 86 and 87 are concerned with penoplast-polychloroprene-hexamethylene-tetramine adhesives which were applied from solution to paper and dried to provide adhesive tapes for use in joining substrates in a press at elevated temperatures. The adhesive formulation of Example 87, which was identical to that of Example 86 except for the addition of m-aminophenol in methylethyl ketone, was found to provide improved wood-paper-wood adhesion.

In the preparation of these adhesives, 6 parts phenolic resin (Bakelite CKM1634, Union Carbide Corp.) and 15 parts polychloroprene (Neoprene AC, E. I. du Pont de Nemours & Co., Inc.) were dissolved in 51 parts toluene, and then a solution of 1.2 parts hexamethylenetetramine in 15 parts chloroform was added. One half of this cement without further additions was used in Example 86, while to the other half (Example 87) was added 1 part m-aminophenol dissolved in 10 parts methylethyl ketone.

These cements were painted onto both sides of strips of filter paper after which the strips of paper were dried at about 27.degree. C. Circles 3/16 inch in diameter were then cut with a cork borer from the two coated papers, and each circle was placed between the over-lapped ends of two flat wooden sticks so that it was at about the midpoint of a one inch overlap of the sticks. These assemblies were wrapped in aluminum foil to hold their members temporarily in place and then were laminated in a small press for 30 minutes at 160.degree. C., using enough pressure (in excess of 60 psi) to insure good contact. The heat was then shut off and the specimens cooled under pressure to 80.degree. C., before the press was opened.

These adhesion test specimens, after cooling, were tested for lap shear tensile strength by the method described for Examples 63-68. The results of these tests, as presented in Table XXIII showed that the addition of m-aminophenol to the adhesive formulation resulted to improved adhesion.

Examples 88 and 89 demonstrate improvement of adhesion obtained by adding m-aminophenol to RFL dips containing a carboxyl-modified butadiene-acrylonitrile elastomer latex where the RFL dips were used in the preparation of papersupported adhesive tapes.

In preparing the RFL dips, 12.8 parts resorcinol were dissolved in 100 parts 1% aqueous sodium hydroxide solution, then 19 parts 37% formalin were added and this mixture was allowed to age for 21/2 hours at about 27.degree. C. before the addition of 150 parts carboxyl-modified KBR latex (Bycar 1570 X 20, B. F. Goodrich Chemical Co.) containing 60 parts solids. This dip was then divided into two equal portions, to the first of which (Example 88) were added 50 parts water, while to the second (Example 89) was added a solution of 3 parts m-aminophenol in 47 parts water.

Strips of filter paper were then dipped into each of the above dispersions and dried 24 hours at about 21.degree. C. Circles of 3/16 inch diameter were cut from each of these strips and placed between the over-lapped ends of flat wooden sticks so that the circles of adhesive tape were about in the center of a one inch overlap of the sticks. Aluminum foil was wrapped around these assemblies to hold their members temporarily in place and then they were laminated together in a small laboratory press for 60 minutes at 160.degree. C. and a pressure sufficient to insure good contact (at least 60 psi).

The cured adhesive specimens, after cooling, were tested for lap shear strength as previously described for Examples 63-68. The results, as presented in Table XXXV, showed that the adhesion of Examples 89, in which m-aminophenol was added to the RFL dip, was superior to that of Example 83 without m-aminophenol.

In Examples 90 and 91, paper-supported adhesive tapes were prepared by dipping strips of filter paper into solutions of a heat-reactive bromo-methyl alkylated, phenolformaldehyde resin (SF-1055 Resin, Schenectady Chemicals Inc.).

A master solution of the resin was first prepared by dissolving 20 parts of the resin in 20 parts each toluene and acetone and then was divided into two equal portions of 30 parts each. To one (Example 90) were added 30 acetone, while to the other (Example 91) was added a solution of 3 parts m-aminophenol in 27 parts acetone. The strips of filter paper dipped in these solutions were dried at about 21.degree. C. for 20 hours.

Circles of 3/16 inch diameter were then out from the paper tapes and were placed between the over-lapping ends of flat wooden sticks so that they were about in the center of a one inch over-lap of the sticks. Aluminum foil was wrapped around these assemblies to hold their members temporarily in place and then they were laminated together in a small laboratory press for 60 minutes at 160.degree. C. and a pressure sufficient to insure good contact (in excess of 60 psi).

The cured adhesive specimens, after cooling, were tested for lap shear strength as described for Examples 63-68. The results of these test, presented in Table XXV showed that the specimen of Example 91 in which the adhesive contained m-aminophenol was superior to that of Example 90 in which no aminophenal was added to the adhesive resin.

Examples 92 and 93 are concerned with thermosetting adhesive formulations containing a novolak phenolic resin and hexamethylenetetramine, and they demonstrate that improved adhesion was obtained by the addition of m-aminophenol to the basic formulation.

The adhesives were prepared and applied to paper supports as follows: 47 parts cashew nut shell oil modified phenolic resin (Duoz 12686, Hooker Chemical Corporation) were dissolved in an equal weight of acetone, and to this solution were added 3.8 parts hexamethylenetetramine dissolved in 50 parts chloroform. This solution was then divided into two equal parts, to the first of which (Example 92) were added 60 parts acetone, while to the second (Example 93) were added a solution of 6 parts m-aminophenol in 54 parts acetone. Strips of filter paper were dipped into each of these solutions and dried 24 hours at about 21.degree. C.

Circles of 3/16 inch diameter were cut from both strips and placed between the overlapped ends of flat wooden sticks so that the circles were about in the center of a one-inch overlap of the sticks. Aluminum foil was wrapped around these assemblies to hold their members temporarily in place and then they were laminated in a small laboratory press for 60 minutes at 160.degree. C. and a pressure in excess of 60 psi, sufficient to insure good contact.

The laminates, after cooling, were then tested for lap shear strength as previously described for examples 63-68. The results of these tests are presented in Table XXVI.

It will further be appreciated by those skilled in the art that in practicing the present invention, the adhesive compositions may include fillers, coloring ingredients, and other additives which do not prevent the attaining of advantages of use of the promoter of the present invention. Such fillers for example are set forth in Carswells Treatise on "Phenoplasts" above referred to, and in the "Handbook of Adhesives" by Irving Shiest, Reinhold (1962), herein incorporated by reference.

While there have been described herein what are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that modifications and changes may be made therein without departing from the essence of the invention. It is therefore understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalents of the claims are intended to be included therein.